Garleton Hills Volcanic Rocks - an excursion - Revision history

Scotfot at 09:36, 7 November 2015

2015-11-07T09:36:17Z

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	[[File:Lothian Geology cover.jpg\|thumb\|100px\|right\|[http://www.edinburghgeolsoc.org/p_sales.html#lothiangeology Buy the book]]]		[[File:Lothian Geology cover.jpg\|thumb\|100px\|right\|[http://www.edinburghgeolsoc.org/p_sales.html#lothiangeology Buy the book]]]

	'''By B.B.J. Upton and R. MacDonald. From: Lothian geology ~~and~~ excursion guide. Edited by A.D. McAdam and E.N.K. Clarkson. 1996'''		'''By B.B.J. Upton and R. MacDonald. From: [[Lothian Geology: an excursion guide\|Lothian geology: an excursion guide]]. Edited by A.D. McAdam and E.N.K. Clarkson. 1996'''

Scotfot: /* At all times follow: The Scottish Access Codeand Code of Conduct for Fieldwork */

2015-03-06T21:22:04Z

At all times follow: The Scottish Access Codeand Code of Conduct for Fieldwork

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	The intrusive tuff is quite dissimilar to the red tuff which outcrops on the south side of the quarry, It is less well sorted in terms of grain-size and variety of components and lacks the opaque fragments of volcanic rock that characterise the red tuff. The fragments of biotite-granite which it contains are of some interest: they possibly have some with the granitic mass of probably Lower Old Red Sandstone age exposed some 500 m to the ESE, on the southern side of the Southern Upland Fault (Simpson 1928).		The intrusive tuff is quite dissimilar to the red tuff which outcrops on the south side of the quarry, It is less well sorted in terms of grain-size and variety of components and lacks the opaque fragments of volcanic rock that characterise the red tuff. The fragments of biotite-granite which it contains are of some interest: they possibly have some with the granitic mass of probably Lower Old Red Sandstone age exposed some 500 m to the ESE, on the southern side of the Southern Upland Fault (Simpson 1928).

	== At all times follow: [http://www.outdooraccess-scotland.com/the-act-and-the-code/introduction The Scottish Access Code]and [http://www.geologistsassociation.org.uk/downloads/Code%20of%20conduct/Code%20for%20fieldwork%20combined.pdf Code of Conduct for Fieldwork] ==		{{EGwalks}}


	[[category:5. Midland Valley of Scotland]]		[[category:5. Midland Valley of Scotland]]

Scotfot at 22:14, 20 February 2015

2015-02-20T22:14:09Z

Scotfot: /* 11. Kidlaw Quarry: Tuffs, Analcime-basanite Intrusion and Peridotite (Lherzolite) Inclusions */

2015-02-16T19:19:56Z

11. Kidlaw Quarry: Tuffs, Analcime-basanite Intrusion and Peridotite (Lherzolite) Inclusions

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	This locality, some 5 km south-west of Gifford and about 13 km south-west of Traprain Law, is reached by a sunken grassy track leading from the junction of the two minor near Kidlaw (NT 506 642) into the disused quarry. On entering the quarry, small outcrops of reddish tuff may be seen on the right-hand bank beside the path. These consist of small (< 5 mm) particles of what appear to be altered volcanic glass. These scoria fragments are very vesicular, often showing deformed and streaked-out vesicles. The matrix between the volcanic fragments consists largely of angular quartz grains and lesser amounts of microcline.		This locality, some 5 km south-west of Gifford and about 13 km south-west of Traprain Law, is reached by a sunken grassy track leading from the junction of the two minor near Kidlaw (NT 506 642) into the disused quarry. On entering the quarry, small outcrops of reddish tuff may be seen on the right-hand bank beside the path. These consist of small (< 5 mm) particles of what appear to be altered volcanic glass. These scoria fragments are very vesicular, often showing deformed and streaked-out vesicles. The matrix between the volcanic fragments consists largely of angular quartz grains and lesser amounts of microcline.

	The quarry itself, however, is mainly cut into a fine-grained tough and well-jointed analcime-basanite (or monchiquitic basalt). From the non-vesicular nature of the mass it is likely to be a hypabyssal intrusion although there is no clear guide to the overall form. Clough et. al. (1910) considered it to be a sill intruded into the Calciferous Sandstone Measures though, on the basis of a vertical contact between tuff and basanite exposed during quarrying operations in the ~~1920•s~~. Simpson (1928) has suggested that it is a plug in a vent. The rock is slightly porphyritic, carrying small scattered phenocrysts of olivine, augite and plagioclase. The groundmass is composed of augite, magnetite, biotite, plagioclase and alkali feldspar with analcime forming poikilitic patches up to 2 mm across. The latter accounts for the speckled appearance of many of the weathered rock surfaces.		The quarry itself, however, is mainly cut into a fine-grained tough and well-jointed analcime-basanite (or monchiquitic basalt). From the non-vesicular nature of the mass it is likely to be a hypabyssal intrusion although there is no clear guide to the overall form. Clough et. al. (1910) considered it to be a sill intruded into the Calciferous Sandstone Measures though, on the basis of a vertical contact between tuff and basanite exposed during quarrying operations in the 1920s. Simpson (1928) has suggested that it is a plug in a vent. The rock is slightly porphyritic, carrying small scattered phenocrysts of olivine, augite and plagioclase. The groundmass is composed of augite, magnetite, biotite, plagioclase and alkali feldspar with analcime forming poikilitic patches up to 2 mm across. The latter accounts for the speckled appearance of many of the weathered rock surfaces.

	The intrusion is of interest in that it contains relatively abundant ultrabasic 'nodules', generally less than 5 cm across and consisting of olivine. enstatite, diopside and spinel in varying stages of alteration, they can be best described as altered spinel lherzolites. On weathered surfaces they 'weather in' to form shallow hollows, often with an associated set of radial cracks in the adjacent host rock.		The intrusion is of interest in that it contains relatively abundant ultrabasic 'nodules', generally less than 5 cm across and consisting of olivine. enstatite, diopside and spinel in varying stages of alteration, they can be best described as altered spinel lherzolites. On weathered surfaces they 'weather in' to form shallow hollows, often with an associated set of radial cracks in the adjacent host rock.

Scotfot: /* 9. Traprain Law: Phonolite Laccolith */

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9. Traprain Law: Phonolite Laccolith

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	The phonolite, though devoid of vesicles on the lower flanks of Traprain, becomes highly vesicular near the summit suggesting that the rock crystallised under near-surface conditions and that the intrusion may even have acted as a feeder for surface extrusions.		The phonolite, though devoid of vesicles on the lower flanks of Traprain, becomes highly vesicular near the summit suggesting that the rock crystallised under near-surface conditions and that the intrusion may even have acted as a feeder for surface extrusions.

	10. Balfour Monument: Craiglockhart Basalt and Kulaite Lavas		==== 10. Balfour Monument: Craiglockhart Basalt and Kulaite Lavas ====

	Take the road east and then south of Traprain Law to the minor road junction (NT 603 739) and then travel westwards to the monument set on a prominent north-facing lava escarpment (NT 575 737). Just as at the Kippielaw escarpment, the arable land between the escarpment and the steep contact wall of the Traprain intrusion lies on Calciferous Sandstone Measures sedimentary rocks.		Take the road east and then south of Traprain Law to the minor road junction (NT 603 739) and then travel westwards to the monument set on a prominent north-facing lava escarpment (NT 575 737). Just as at the Kippielaw escarpment, the arable land between the escarpment and the steep contact wall of the Traprain intrusion lies on Calciferous Sandstone Measures sedimentary rocks.

Scotfot: /* 9. Traprain Law: Phonolite Laccolith */

2015-02-16T19:16:43Z

9. Traprain Law: Phonolite Laccolith

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	The dome-shaped mass of Traprain Law appears to reflect the form of the upper surface of the intrusion virtually unmodified by erosion. In the large road-metal quarry (NT 584 750) on the north-east side of the hill, a prominent set of joints lies approximately parallel to the contacts. The intrusion is generally believed to have a laccolithic form and to have been responsible for arching up the surrounding sediments and lavas. The phonolite exhibits considerable variety in terms of colour and texture (Tomkeieff 1952). Pronounced flow-banding can be seen on the cast face of the quarry, involving layers of grey rock and layers of a pinker, more speckled variety. There is some evidence that the pink bands owe their origin to a slight hydrothermal alteration of the grey. Sedimentary xenoliths, mainly of black shale and sandstone in varying states of assimilation, are common in the intrusion, blocks up to 10 m long having been recovered by Day (1929). Xenoliths of basic igneous rocks, including an unusual analcime-trachybasalt (Tomkeieff 1952) arc much scarcer.		The dome-shaped mass of Traprain Law appears to reflect the form of the upper surface of the intrusion virtually unmodified by erosion. In the large road-metal quarry (NT 584 750) on the north-east side of the hill, a prominent set of joints lies approximately parallel to the contacts. The intrusion is generally believed to have a laccolithic form and to have been responsible for arching up the surrounding sediments and lavas. The phonolite exhibits considerable variety in terms of colour and texture (Tomkeieff 1952). Pronounced flow-banding can be seen on the cast face of the quarry, involving layers of grey rock and layers of a pinker, more speckled variety. There is some evidence that the pink bands owe their origin to a slight hydrothermal alteration of the grey. Sedimentary xenoliths, mainly of black shale and sandstone in varying states of assimilation, are common in the intrusion, blocks up to 10 m long having been recovered by Day (1929). Xenoliths of basic igneous rocks, including an unusual analcime-trachybasalt (Tomkeieff 1952) arc much scarcer.

	[[Image:P000690.jpg\|thumb\|200px\| ~~vvvvv~~]]		[[Image:P000690.jpg\|thumb\|200px\| Traprain Law, a phonolite laccolith intruded into Lower Carboniferous sediments and volcanic rocks which form the drift-covered foreground. Taken from Balfour Monument at Blaikie Heugh, 3 km. south-west of East Linton. [http://geoscenic.bgs.ac.uk/asset-bank/action/viewAsset?id=1989 P000690]]]

	The phonolite contains phenocrysts of oligoclase and cryptoperthite with small, scarce phenocrysts of clinopyroxene, apatite and much-oxidized and corroded hornblende. The matrix consists of antiperthite, aegirine-augite, fayalite, sodalite and magnetite. The presence of small quantities of nepheline has also been reported (MacGregor and Ennos 1922). Late crystallising components, largely concentrated into thin veinlets include analcime, calcite, apophyllite and alkali feldspar. Prehnite, pectolite, natrolite, datolite, anhydrite, selenite and stilpnomelane have also been recorded.		The phonolite contains phenocrysts of oligoclase and cryptoperthite with small, scarce phenocrysts of clinopyroxene, apatite and much-oxidized and corroded hornblende. The matrix consists of antiperthite, aegirine-augite, fayalite, sodalite and magnetite. The presence of small quantities of nepheline has also been reported (MacGregor and Ennos 1922). Late crystallising components, largely concentrated into thin veinlets include analcime, calcite, apophyllite and alkali feldspar. Prehnite, pectolite, natrolite, datolite, anhydrite, selenite and stilpnomelane have also been recorded.

Scotfot: /* 9. Traprain Law: Phonolite Laccolith */

2015-02-16T19:15:05Z

9. Traprain Law: Phonolite Laccolith

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	The dome-shaped mass of Traprain Law appears to reflect the form of the upper surface of the intrusion virtually unmodified by erosion. In the large road-metal quarry (NT 584 750) on the north-east side of the hill, a prominent set of joints lies approximately parallel to the contacts. The intrusion is generally believed to have a laccolithic form and to have been responsible for arching up the surrounding sediments and lavas. The phonolite exhibits considerable variety in terms of colour and texture (Tomkeieff 1952). Pronounced flow-banding can be seen on the cast face of the quarry, involving layers of grey rock and layers of a pinker, more speckled variety. There is some evidence that the pink bands owe their origin to a slight hydrothermal alteration of the grey. Sedimentary xenoliths, mainly of black shale and sandstone in varying states of assimilation, are common in the intrusion, blocks up to 10 m long having been recovered by Day (1929). Xenoliths of basic igneous rocks, including an unusual analcime-trachybasalt (Tomkeieff 1952) arc much scarcer.		The dome-shaped mass of Traprain Law appears to reflect the form of the upper surface of the intrusion virtually unmodified by erosion. In the large road-metal quarry (NT 584 750) on the north-east side of the hill, a prominent set of joints lies approximately parallel to the contacts. The intrusion is generally believed to have a laccolithic form and to have been responsible for arching up the surrounding sediments and lavas. The phonolite exhibits considerable variety in terms of colour and texture (Tomkeieff 1952). Pronounced flow-banding can be seen on the cast face of the quarry, involving layers of grey rock and layers of a pinker, more speckled variety. There is some evidence that the pink bands owe their origin to a slight hydrothermal alteration of the grey. Sedimentary xenoliths, mainly of black shale and sandstone in varying states of assimilation, are common in the intrusion, blocks up to 10 m long having been recovered by Day (1929). Xenoliths of basic igneous rocks, including an unusual analcime-trachybasalt (Tomkeieff 1952) arc much scarcer.

			[[Image:P000690.jpg\|thumb\|200px\| vvvvv]]

	The phonolite contains phenocrysts of oligoclase and cryptoperthite with small, scarce phenocrysts of clinopyroxene, apatite and much-oxidized and corroded hornblende. The matrix consists of antiperthite, aegirine-augite, fayalite, sodalite and magnetite. The presence of small quantities of nepheline has also been reported (MacGregor and Ennos 1922). Late crystallising components, largely concentrated into thin veinlets include analcime, calcite, apophyllite and alkali feldspar. Prehnite, pectolite, natrolite, datolite, anhydrite, selenite and stilpnomelane have also been recorded.		The phonolite contains phenocrysts of oligoclase and cryptoperthite with small, scarce phenocrysts of clinopyroxene, apatite and much-oxidized and corroded hornblende. The matrix consists of antiperthite, aegirine-augite, fayalite, sodalite and magnetite. The presence of small quantities of nepheline has also been reported (MacGregor and Ennos 1922). Late crystallising components, largely concentrated into thin veinlets include analcime, calcite, apophyllite and alkali feldspar. Prehnite, pectolite, natrolite, datolite, anhydrite, selenite and stilpnomelane have also been recorded.
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	The lava forming the main scarp feature here is some 15 m thick and shows a roughly columnar jointing pattern. It is an ankaramitic basalt, rich in large augite crystals (up to 1 cm) and conspicuous brown pseudomorphs after olivine (up to 0.5 cm). This rock, following MacGregor's (1928) classification, is a basalt of Craiglockhart type.		The lava forming the main scarp feature here is some 15 m thick and shows a roughly columnar jointing pattern. It is an ankaramitic basalt, rich in large augite crystals (up to 1 cm) and conspicuous brown pseudomorphs after olivine (up to 0.5 cm). This rock, following MacGregor's (1928) classification, is a basalt of Craiglockhart type.

	A subordinate scarp feature, below and some way east of the monument, is formed from an underlying trachybasaltic flow. This much decomposed rock, which has been called a kulaite, contains a high concentration of pseudomorphed (oxidised) hornblende phenocrysts. In the fine-grained matrix, plagioclase and analcime are among the least altered components.		A subordinate scarp feature, below and some way east of the monument, is formed from an underlying trachybasaltic flow. This much decomposed rock, which has been called a kulaite, contains a high concentration of pseudomorphed (oxidised) hornblende phenocrysts. In the fine-grained matrix, plagioclase and analcime are among the least altered components.

	==== 11. Kidlaw Quarry: Tuffs, Analcime-basanite Intrusion and Peridotite (Lherzolite) Inclusions ====		==== 11. Kidlaw Quarry: Tuffs, Analcime-basanite Intrusion and Peridotite (Lherzolite) Inclusions ====

Scotfot at 19:04, 16 February 2015

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	The excursion commences among the trachyte lavas of the Garleton Hills, proceeds on to the basic lavas beneath the trachytes in the vicinity of East Linton and then moves south to Traprain Law and finally to Kidlaw, not far from Gifford. Private transport is essential to complete the excursion in one day.		The excursion commences among the trachyte lavas of the Garleton Hills, proceeds on to the basic lavas beneath the trachytes in the vicinity of East Linton and then moves south to Traprain Law and finally to Kidlaw, not far from Gifford. Private transport is essential to complete the excursion in one day.

	[[Image:GarletonHillsVolcanicRocksExcursionMap.jpg\|thumb\|~~500px~~\|Garleton Hills Volcanic Rocks excursion map]]		[[Image:GarletonHillsVolcanicRocksExcursionMap.jpg\|thumb\|600px\|center\|Garleton Hills Volcanic Rocks excursion map]]

	==== 1. Bangly Quarry: Trachytic Lava and Dyke ====		==== 1. Bangly Quarry: Trachytic Lava and Dyke ====

Scotfot at 19:03, 16 February 2015

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	Basaltic tuffs 200 m		Basaltic tuffs 200 m

	Whereas the basaltic and mugearitic lavas and the basal ash-beds are well exposed on the coast at North Berwick (p. 88), this excursion is principally concerned with the inland outcrops in the vicinity of the Garleton Hills and Traprain Law. In this region, the basal ashes are thin and largely unexposed, but the basic and trachytic lavas can be easily examined in numerous quarries and natural outcrops. Intrusive phonolite may be examined at Traprain Law, where Pleistocene glaciation has deeply eroded the softer Carboniferous sedimentary rocks and left the tough intrusive rocks as a prominent high-point in the landscape. The ~~excursion~~ also includes one of the late Carboniferous quartzdolerite dykes (Bangly Hill). A presumed intrusive mass of silica-undersaturated basalt (basanite) containing peridotite inclusions and cut by intrusive tuff is seen at Kidlaw.		Whereas the basaltic and mugearitic lavas and the basal ash-beds are well exposed on the coast at North Berwick (p. 88), this excursion is principally concerned with the inland outcrops in the vicinity of the Garleton Hills and Traprain Law. In this region, the basal ashes are thin and largely unexposed, but the basic and trachytic lavas can be easily examined in numerous quarries and natural outcrops. Intrusive phonolite may be examined at Traprain Law, where Pleistocene glaciation has deeply eroded the softer Carboniferous sedimentary rocks and left the tough intrusive rocks as a prominent high-point in the landscape. The excursion also includes one of the late Carboniferous quartzdolerite dykes (Bangly Hill). A presumed intrusive mass of silica-undersaturated basalt (basanite) containing peridotite inclusions and cut by intrusive tuff is seen at Kidlaw.

	The excursion commences among the trachyte lavas of the Garleton Hills, proceeds on to the basic lavas beneath the trachytes in the vicinity of East Linton and then moves south to Traprain Law and finally to Kidlaw, not far from Gifford. Private transport is essential to complete the excursion in one day.		The excursion commences among the trachyte lavas of the Garleton Hills, proceeds on to the basic lavas beneath the trachytes in the vicinity of East Linton and then moves south to Traprain Law and finally to Kidlaw, not far from Gifford. Private transport is essential to complete the excursion in one day.

			[[Image:GarletonHillsVolcanicRocksExcursionMap.jpg\|thumb\|500px\|Garleton Hills Volcanic Rocks excursion map]]

	==== 1. Bangly Quarry: Trachytic Lava and Dyke ====		==== 1. Bangly Quarry: Trachytic Lava and Dyke ====

Scotfot at 18:58, 16 February 2015

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	B.G.S. 1:50000 Sheet 33W Haddington		B.G.S. 1:50000 Sheet 33W Haddington
	Route: Map 13		Route: Map 13

			====Introduction====

	Contemporaneous with the Lower Carboniferous volcanics that crop out in and around Edinburgh (p. 33), are volcanic rocks which re-appear some 32 km east of the city in the vicinity of North Berwick and the Garleton Hills. The succession is thicker, and with the presence of trachytes, more varied than that of the Arthur's Sent Volcanic Rocks in Edinburgh. The Garleton Hills Volcanic Rocks lie within the Calciferous Sandstone Measures. A generalised succession is as follows:		Contemporaneous with the Lower Carboniferous volcanics that crop out in and around Edinburgh (p. 33), are volcanic rocks which re-appear some 32 km east of the city in the vicinity of North Berwick and the Garleton Hills. The succession is thicker, and with the presence of trachytes, more varied than that of the Arthur's Sent Volcanic Rocks in Edinburgh. The Garleton Hills Volcanic Rocks lie within the Calciferous Sandstone Measures. A generalised succession is as follows:

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	Basaltic tuffs 200 m		Basaltic tuffs 200 m

	Whereas the basaltic and mugearitic lavas and the basal ash-beds are well exposed on the coast at North Berwick (p. 88), this excursion is principally concerned with the inland outcrops in the vicinity of the Garleton Hills and Traprain Law. In this region, the basal ashes are thin and largely unexposed, but the basic and trachytic lavas can be easily examined in numerous quarries and natural outcrops. Intrusive phonolite may be examined at Traprain Law, where Pleistocene glaciation has deeply eroded the softer Carboniferous sedimentary rocks and left the tough intrusive rocks as a prominent high-point in the landscape. The excursion also includes one of the late Carboniferous ~~quartzdolerite~~ dykes (Bangly Hill). A presumed intrusive mass of silica-undersaturated basalt (basanite) containing peridotite inclusions and cut by intrusive tuff is seen at Kidlaw.		Whereas the basaltic and mugearitic lavas and the basal ash-beds are well exposed on the coast at North Berwick (p. 88), this excursion is principally concerned with the inland outcrops in the vicinity of the Garleton Hills and Traprain Law. In this region, the basal ashes are thin and largely unexposed, but the basic and trachytic lavas can be easily examined in numerous quarries and natural outcrops. Intrusive phonolite may be examined at Traprain Law, where Pleistocene glaciation has deeply eroded the softer Carboniferous sedimentary rocks and left the tough intrusive rocks as a prominent high-point in the landscape. The excursion also includes one of the late Carboniferous quartz-dolerite dykes (Bangly Hill). A presumed intrusive mass of silica-undersaturated basalt (basanite) containing peridotite inclusions and cut by intrusive tuff is seen at Kidlaw.

	The excursion commences among the trachyte lavas of the Garleton Hills, proceeds on to the basic lavas beneath the trachytes in the vicinity of East Linton and then moves south to Traprain Law and finally to Kidlaw, not far from Gifford. Private transport is essential to complete the excursion in one day.		The excursion commences among the trachyte lavas of the Garleton Hills, proceeds on to the basic lavas beneath the trachytes in the vicinity of East Linton and then moves south to Traprain Law and finally to Kidlaw, not far from Gifford. Private transport is essential to complete the excursion in one day.
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	==== 8. Kippielaw Scarp: Basalt and Mugearite Lavas ====		==== 8. Kippielaw Scarp: Basalt and Mugearite Lavas ====

	The route now continues eastwards across the River Tyne to the junction (NT 593 768) of the A1 and the minor road ~~leading~~ south towards Traprain Farm. Scattered outcrops seen at this junction and in the fields to the south-east are in basalt lavas low in the volcanic succession. At Traprain Farm (NT 592 757) the minor road leading westwards towards Kippielaw Farm should be followed for about 200 m until, beyond a patch of woodland, there is access to a low southward-facing escarpment. At this vantage point a good view may be had of the surrounding countryside. To the north rise the prominent phonolitic trachyte plugs of North Berwick Law and Bass Rock and to the west, across the Tyne Valley, are the trachytes of the Garleton Hills. Arthur's Seat can be seen still farther west where the Lower Carboniferous lavas re-emerge on the western limb of the Midlothian coalfield.		The route now continues eastwards across the River Tyne to the junction (NT 593 768) of the A1 and the minor road leading south towards Traprain Farm. Scattered outcrops seen at this junction and in the fields to the south-east are in basalt lavas low in the volcanic succession. At Traprain Farm (NT 592 757) the minor road leading westwards towards Kippielaw Farm should be followed for about 200 m until, beyond a patch of woodland, there is access to a low southward-facing escarpment. At this vantage point a good view may be had of the surrounding countryside. To the north rise the prominent phonolitic trachyte plugs of North Berwick Law and Bass Rock and to the west, across the Tyne Valley, are the trachytes of the Garleton Hills. Arthur's Seat can be seen still farther west where the Lower Carboniferous lavas re-emerge on the western limb of the Midlothian coalfield.

	About 1 km south of the escarpment, the steep-sided Traprain Law rises out of fields underlain by rocks of the Calciferous Sandstone Measures. These rocks are brought up in the core of the anticlinal structure created by the Traprain Law intrusion.		About 1 km south of the escarpment, the steep-sided Traprain Law rises out of fields underlain by rocks of the Calciferous Sandstone Measures. These rocks are brought up in the core of the anticlinal structure created by the Traprain Law intrusion.

	Three or four kilometres beyond Traprain is the fault-line scarp of the Southern Uplands where barren moorlands mark the outcrop of the older Lower Palaeozoic shales and greywackes and contrast with the cultivated farmlands ~~overlying~~ the younger Upper Palaeozoic sediments in the foreground and middle distance.		Three or four kilometres beyond Traprain is the fault-line scarp of the Southern Uplands where barren moorlands mark the outcrop of the older Lower Palaeozoic shales and greywackes and contrast with the cultivated farmlands overlying the younger Upper Palaeozoic sediments in the foreground and middle distance.

	The mugearite now near Traprain Farm lies low in the lava sequence. The lavas themselves are separated from the underlying Calciferous Sandstone Measures by a horizon of ashes, correlative with the thick basal ash sequence so well seen on the foreshore at North Berwick. The ash-horizon here, however, is much attenuated and largely unexposed; if time permits it may be examined later in the uncultivated fields to the west of Kippielaw Farm, around NT 580 755.		The mugearite now near Traprain Farm lies low in the lava sequence. The lavas themselves are separated from the underlying Calciferous Sandstone Measures by a horizon of ashes, correlative with the thick basal ash sequence so well seen on the foreshore at North Berwick. The ash-horizon here, however, is much attenuated and largely unexposed; if time permits it may be examined later in the uncultivated fields to the west of Kippielaw Farm, around NT 580 755.
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	==== 9. Traprain Law: Phonolite Laccolith ====		==== 9. Traprain Law: Phonolite Laccolith ====

	The dome-shaped mass of Traprain Law appears to reflect the form of the upper surface of the intrusion virtually ~~unmodified~~ by erosion. In the large road-metal quarry (NT 584 750) on the north-east side of the hill, a prominent set of joints lies approximately parallel to the contacts. The intrusion is generally believed to have a laccolithic form and to have been responsible for arching up the surrounding sediments and lavas. The phonolite exhibits considerable variety in terms of colour and texture (Tomkeieff 1952). Pronounced flow-banding can be seen on the cast face of the quarry, involving layers of grey rock and layers of a pinker, more speckled variety. There is some evidence that the pink bands owe their origin to a slight hydrothermal alteration of the grey. Sedimentary xenoliths, mainly of black shale and sandstone in varying states of assimilation, are common in the intrusion, blocks up to 10 m long having been recovered by Day (1929). Xenoliths of basic igneous rocks, including an unusual analcime-trachybasalt (Tomkeieff 1952) arc much scarcer.		The dome-shaped mass of Traprain Law appears to reflect the form of the upper surface of the intrusion virtually unmodified by erosion. In the large road-metal quarry (NT 584 750) on the north-east side of the hill, a prominent set of joints lies approximately parallel to the contacts. The intrusion is generally believed to have a laccolithic form and to have been responsible for arching up the surrounding sediments and lavas. The phonolite exhibits considerable variety in terms of colour and texture (Tomkeieff 1952). Pronounced flow-banding can be seen on the cast face of the quarry, involving layers of grey rock and layers of a pinker, more speckled variety. There is some evidence that the pink bands owe their origin to a slight hydrothermal alteration of the grey. Sedimentary xenoliths, mainly of black shale and sandstone in varying states of assimilation, are common in the intrusion, blocks up to 10 m long having been recovered by Day (1929). Xenoliths of basic igneous rocks, including an unusual analcime-trachybasalt (Tomkeieff 1952) arc much scarcer.

	[[Image:P000690.jpg\|thumb\|200px\| Traprain Law, a phonolite laccolith intruded into Lower Carboniferous sediments and volcanic rocks which form the drift-covered foreground. Taken from Balfour Monument at Blaikie Heugh, 3 km. south-west of East Linton. [http://geoscenic.bgs.ac.uk/asset-bank/action/viewAsset?id=1989 P000690]]]		[[Image:P000690.jpg\|thumb\|200px\| Traprain Law, a phonolite laccolith intruded into Lower Carboniferous sediments and volcanic rocks which form the drift-covered foreground. Taken from Balfour Monument at Blaikie Heugh, 3 km. south-west of East Linton. [http://geoscenic.bgs.ac.uk/asset-bank/action/viewAsset?id=1989 P000690]]]